The present invention relates to multiplexers. The present invention also relates to one-time programmable (OTP) solid state memory.
Portable devices such as PDAs, handheld computers, digital cameras and digital music players include memory for storing data, digital images and MP3 files. Different types of memory are available for these portable devices. Conventional memory types include flash memory, mini-hard drives, mini-compact discs, and magnetic tape. However, each of these memory types has one or more of the following limitations: large physical size, low storage capacity, relatively high cost, poor robustness, slow access time and high power consumption.
Solid state diode-based OTP memory is disclosed in assignee""s U.S. Ser. No. 09/875,356 filed Jun. 5, 2001. Compared to the conventional memory, the diode-based memory has a high shock tolerance, low power consumption, fast access time, moderate transfer rate and good storage capacity. The diode-based memory can fit into a standard portable interface (e.g., PCMCIA, CF) of a portable device.
Solid state diode-based OTP memory devices can include large numbers of data and address lines. Multiplexers may be used to reduce the number of data and address lines to a device.
The multiplexers may be based on transistor logic such as TTL. However, manufacturing the layers required for transistors in a diode-based OTP device would increase the cost and complexity of the device.
It would be desirable to avoid the use of transistors in multiplexers of diode-based OTP memory devices.
According to one aspect of the present invention, a multiplexer includes a plurality of stages. Each stage includes a storage device coupled to a data output; a first diode coupled between a data input and a power supply input; and a second diode coupled between the power supply input and the data output.
Other aspects and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the present invention.